1. Field of the Invention
The present invention pertains to tools for use in measuring and marking material, and, more particularly, to a transparent ruler having composite lines with apertures for viewing underlying material.
2. Description of the Related Art
Transparent rulers having grid lines formed thereon are known for use in measuring and marking material, such as fabric, paper, plastic, and the like. These rulers are also used to guide a tool, such as a razor, knife, or rotary cutter, in cutting the material to desired sizes and shapes.
Most rulers use single color opaque markings for aligning material for measurement and cutting. The opaque line, which is usually black, interferes with viewing the underlying material, which can cause inaccurate alignment, marking, and cutting. The utilization of a single color line makes the ruler less versatile for use on light and dark materials. This was solved by superimposing another contrasting wider line behind the first line.
One such ruler is that described in U.S. Pat. No. 4,779,346 for a transparent measuring device that includes a plurality of continuous two-color lines of contrasting colors. In use, these lines are visible against a background of multiple colors, thus facilitating the measuring and marking of underlying material.
Although this ruler has markings that are now more versatile, these markings are wider and provide more interference with viewing the material on which the ruler is placed. For example, a user will have difficulty in visually aligning the underlying material with the line. One approach is to use dashed lines to solve this. However, if the dashed lines are of a single color they will only be visible on either a light or dark material. Superimposing the line with a contrasting color improves visibility but interferes with seeing the underling material. Making the line transparent also helps, but it is still difficult for the user to accurately see what is underneath the ruler.